1. Field of the Invention
The present invention relates to an improvement in an optical device which switches light transmission paths.
2. Prior Arts
One typical example of the conventional light path switching device is constructed as shown in FIG. 1, wherein a first optical fiber 1 is connected to a moving piece 2 of a magnetically responsive material such as iron and second and third optical fibers 5 and 5' are fixed on respective supporting members 4 and 4', which are secured on opposite inner walls of a box 41. A pair of coils 3 and 3' are provided so as to induce a magnetic force at excitation by currents therethrough to drive the moving piece 2 either to the side of the supporting member 4 or to that of the supporting member 4' responding to polarity of the currents. By driving the moving piece 2, the end face of the first optical fiber 1 is put in front of the end face of the second optical fiber 5 or that of the third optical fiber 5', so that light is transmitted from the optical fiber 1 to the optical fiber 5 or to the optical fiber 5'.
The abovementioned conventional light path switch has such shortcomings that the end part of the first optical fiber 1 is liable to damage in a relatively short time due to repeated shocks when driven between the supporting members 4 and 4', that a considerable gap is necessary between the end faces of the first and the second optical fibers 1 and 5 or between those of the first and the third optical fibers 1 and 5', and that it is difficult to construct a light path switch capable of selectively switching among three or more light paths.
Though there is known a light path switching device utilizing a lens system, it is too large and has an excessive loss of light for practical use.